GB2493380A

GB2493380A - A method of calibrating a selected gear sensor

Info

Publication number: GB2493380A
Application number: GB1113410.3A
Authority: GB
Inventors: Ian Halleron; Martin Robekowski; Themi Philemon Petridis
Original assignee: Ford Global Technologies LLC
Current assignee: Ford Global Technologies LLC
Priority date: 2011-08-04
Filing date: 2011-08-04
Publication date: 2013-02-06
Anticipated expiration: 2031-08-04
Also published as: CN102913616B; DE102012213232A1; RU2012133527A; GB201113410D0; RU2588699C2; DE102012213232B4; RU2588699C9; GB2493380B; CN102913616A

Abstract

A method of calibrating a selected gear sensor 7 in a multi-speed manual transmission (3, fig 1) having a gear shift lever (11) by which a driver may select, using an H-gate shift mechanism, various gears. A power train control module (4) has a transmission state module (5) which receives signals from the selected gear sensor 7 that is attached to transmission casing 3B. The sensor 7 is a single 2D magnetic PWM sensor array that provides based upon variations in flux of a magnetic target 8 associated with turret selector cylinder 3A. In the method the output from the selected gear sensor 7 in a gear engaging direction (Y axis) is analysed for the existence of characteristic velocities which are used to define a calibration value corresponding to a gear pull-in position OPI, EPI. The value of the calibration value is updated when a gear shift occurs and the updated value is used by a transmission state module 5 for the next gear shift to predict a next to be engaged gear.

Description

A Method for Calibrating a Selected Gear Sensor This invention relates to a motor vehicle having a manual transmission and in particular to a method for calibrating a selected gear sensor for the transmission.

It is known to provide a gear sensor that provides a signal which can be used by electronic control apparatus of a motor vehicle to determine which gear is ourrently engaged. Such in-gear switches including reverse gear switches can be used to indicate instantaneous gear position. However, such switches only measure discrete gear positions after the gear has been engaged and cannot give any information about an intended gear change, e.g., which gear is the driver changing into. This information is very useful and can give a vehicle control system early indication of the gear change intentions of a driver and therefore allow the system to respond to the driver's demand more quickly.

Also, most in-gear switches are installed outside the transmission so as to sense gear lever position, and as such are subject to non-constant inaccuracies due to large tolerances and changes in gear lever position during the life of the vehicle due to wear.

During some operations of a motor vehicle transmission such as a gear change with such known gear sensors there is consequently a period of time in which the gear to be selected is not known and the gear selected is only known when it is finally engaged.

It is also known to use vehicle speed and engine speed comparison to obtain the gear position that the transmission is currently in. However, this method is not usable when the driveline is disengaged such as when the clutch pedal is pressed and so during a gear change operation any new gear position calculations have to be delayed until the change is complete, that is to say, the gear is fully selected and the clutch is re-engaged.

In addition, the use of vehicle speed and engine speed comparison techniques are unreliable when the vehicle is slipping or skidding such as may occur on a low friction road surface.

Any delays in acquiring information regarding the engaged gear can be problematic for those vehicle control systems which need gear information such as Gear Shift Harmonization (GSH) . GSH is a technique in which the engine speed is matched to the selected gear during a gear change in order to smooth the transitions between gears.

Delayed or inaccurate gear information can also adversely affect other systems requiring gear information. For example, delays in the communication of gear information to a Human Machine Interface (Ht'lI) where gear information is displayed in an instrument cluster can directly affect customer satisfaction.

It has been proposed by the applicants in a co-pending application to provide a selected gear sensor that can provide an output from which a gear to be selected can be predicted before the gear is actually engaged.

It is an object of the invention to provide a method for calibrating such a selected gear sensor so that can be more effectively used to predict a gear to be engaged before it is actually engaged.

According to a first aspect of the invention there is provided a method for calibrating a selected gear sensor for a multi-speed manual transmission having an H-gate shift mechanism in which the selectable gears are arranged in two rows and in a plurality of parallel gear shift lever planes and the shift mechanism includes a shift selector member that is moveable by a gear shift lever in rotational and axial directions to effect engagement of the selectable gears wherein the method comprises monitoring the movement of the shift selector during a gear shift using the selected gear sensor to provide an output indicative of the motion of the shift selector member in a gear engaging direction converting the motion in the gear engaging direction into a velocity in the gear engaging direction and using pre-defined characteristic changes in velocity to produce a calibration value in the gear engaging direction.

Producing a calibration value may comprise locating the position where a peak velocity occurs and using the location that the peak velocity occurs as the calibration value.

Producing may further comprise using a period of substantially zero velocity followed by a spike in velocity to identify the position where the peak velocity occurs.

The method may further comprise using the output from the selected gear sensor to confirm that the shift selector member is moving away from a neutral gear position and only producing a calibration value if the shift selector member is confirmed to be moving away from the neutral position.

The method may further comprise updating the calibration value after every gear shift.

Updating may comprise combining the latest calibration value with a previous calibration value to produce the updated calibration value.

The method may further comprise producing a first calibration value for all of the gears arranged in one row of the two rows of gears and producing a second calibration value for all of the gears in the other row of the two rows of gears.

The method may further comprise producing a separate calibration value for all of the gears.

The calibration value may correspond to a pull-in position.

The shift selector member may be moved in a rotational direction to produce motion in & gear engaging direction and the calibration value corresponds to a rotational position of the shift selector member.

Alternatively, the shift selector member may be moved in an axial direction to produce motion in a gear engaging direction and the calibration value may correspond to an axial position of the shift selector member.

According to a second aspect of the invention there is provided a selected gear sensing system for a multi-speed manual transmission having a H-gate shift mechanism including a shift selector member that is moveable in response to movement of a gear shift lever in rotational and axial directions wherein the system comprises a first sensor to sense rotational motion of the shift selector member, a second sensor to sense axial motion of the shift selector member and an electronic processing unit to receive and process the signals from the first and second sensors, the electronic processing unit being operable to monitor the movement of the shift selector during a gear shift using the selected gear sensor to provide an output indicative of the motion of the shift selector member in a gear engaging direction, convert the motion in the gear engaging direction into a velocity in the gear engaging direction and use pre-defined characteristic changes in velocity to produce a calibration value in the gear engaging direction.

The electronic processing unit may be further operable to use the output from the selected gear sensor to confirm that the shift selector member is moving away from a neutral gear position and only producing a calibration value if the shift selector member is confirmed to be moving away from the neutral position.

The electronic processing unit may be operable to update the calibration value after every gear shift.

The electronic processing unit may be operable to produce a first calibration value for all of the gears arranged in one row of the two rows of gears and producing a second calibration value for all of the gears in the other row of the two rows of gears.

Alternatively, the electronic processing unit may be operable to produce a separate calibration value for all of the gears.

The calibration value may correspond to a pull-in position.

The shift selector member may be moved in a rotational direction to produce motion in a gear engaging direction and the calibration value may correspond to a rctational position of the shift selector member.

According to a third aspect of the invention there is provided a motor vehicle having a predictive selected gear sensing system constructed in accordance with said second aspect of the invention.

The invention will now be described by way of example with reference to the accompanying drawing of which:-Fig.l is a diagrammatic representation of a motor vehicle according to one aspect of the invention; Fig.2A is a diagrammatic view of part of a transmission of the motor vehicle shown in Fig.l showing the location of a 2D selected gear sensor and a 2D magnetic target; Fig.2B is a pictorial view showing the motion of a transmission turret shift selector cylinder, the axial (X axis) and rotational (Y axis) positions of which are sensed by the 2D selected gear sensor; Fig.3A is a first pictorial view of a turret selector cylinder follower; Fig.3B is a second pictorial view of the turret selector cylinder follower shown in Fig.3A; Fig.4 is a pictorial view of a transmission turret shift mechanism showing in more detail the turret selector cylinder shown in Fig.2B; Fig.5 is a more detailed view of the part of the transmission shown in Fig.2A showing the location of the 2D target and the 2D magnetic sensor array; Fig.6A is an enlarged cross-section through part of the turret selector cylinder follower shown in Figs.3A and 3B showing the turret selector follower in a Neutral gear position; Fig.63 is an enlarged cross-section through part of the turret selector cylinder follower shown in Figs.3A and 3B showing the turret selector follower in an Even gear pull-in position; is Fig.60 is an enlarged cross-section through part of the turret selector cylinder follower shown in Figs.3A and 3B showing the turret selector follower in an odd gear pull-in position; Fig.7A is diagram showing the relationship between transmission turret selector cylinder rotational and axial positions and the respective signal outputs from the 2D selected gear sensor; Fig.7B is an enlarged view of the relationship between transmission turret selector cylinder rotational position and signal output showing two in plane or rotational check positions EPI and OPT according to one embodiment of a predictive gear sensing system according to the invention; Fig.8A is a graph of the displacement output from a Y' axis selected gear sensor versus time for a first gear to second gear shift; Fig.8B is a graph of velocity versus time based upon the displacement output shown in Fig.8A; and Fig.9 is a simplified flow chart of a first embodiment of a method for calibrating a selected gear sensor according to the invention.

Referring firstly to Figs 1 to 6C there is shown a motor vehicle 1 having an engine 2 drivingly connected to a manual gearbox/ transmission 3 via a olutch 10. The transmission 3 includes a gear shift lever 11 by which the driver may select using an H-gate selector mechanism the various gears of the transmission 3.

An electronic processing unit in the form of a Powertrain Control Module (PCM) 4 is provided to control the powertrain of the motor vehicle 1. The PCM 4 includes an engine control unit 6 to control the operation of the engine 2 and a transmission state module 5 to determine the operating state of the transmission 3.

The PCM 4 is arranged to receive a number of inputs or signals from sensors 9 including one or more of engine speed from an engine speed sensor, vehicle speed from a vehicle speed sensor, clutch pedal position from a pedal sensor, accelerator pedal position from a pedal sensor, brake pedal position from a pedal sensor and may also receive information regarding other components on the motor vehicle 1 such as the state of charge of a battery (not shown) and the operating state of an air conditioning unit (not shown) Some or all of the inputs from the sensors 9 may be used by engine control unit 6 to control the operation of the engine 2. It will be appreciated that the engine control unit 6 and the transmission state module 5 could be separate processing units or be formed as part of a single electronic processor such as the PCF4 4 as shown.

The motor vehicle 1 inoludes a predictive gear sensing system comprised of the transmission state module 5, a 2D magnetic target 8 and a 2D selected gear sensor 7 forming in combination a 2D selected gear sensor pair. The transmission state module 5 is arranged to receive signals from the selected gear sensor 7 attached to a casing 33 of the transmission 3. The selected gear sensor 7 is a 2D magnetic PWF4 sensor array that provides signals based upon variations in flux between the selected gear sensor 7 and the 213 magnetic target 8 associated with a shift selector member in the form of a turret selector cylinder 3A. The selected gear sensor 7 combines a rotary position sensor and an axial displacement sensor in a single 25 sensor array.

Figs.2A, 4 and 5 shows a typical H-gate' transmission configuration consisting of a shifter turret selector cylinder 3A located inside the main transmission casing 33.

The shift turret selector cylinder 3A rotates when the gear lever 11 is moved forwards and backwards to select respectively odd and even gears and it moves axially when the gear lever U is moved left and right to change the gear shift lever plane in which the gear lever moves. Reverse gear can be configured as an odd gear or an even gear depending upon the configuration of the transmission 3. It will be appreciated that the shifter turret selector cylinder 3A could be arranged such that forward and backward movement results in axial movement of the selector cylinder and left right movement results in rotation of the selector cylinder and the output from the 2D sensor array would be interpreted accordingly.

The gear shift lever 11 is connected by a cable drive to a pair of levers 21A, 213 formed as part of the shifter turret assembly 20 which actuate the shifter turret selector cylinder 3A.

-10 -The 23 magnetic target 8 is attached to the shifter turret selector cylinder 3A and the selected gear sensor 7 is located on the outside of the transmission housing SB and detects axial and rotational movement of the magnetic target 8. However, it will be appreciated that the selected gear sensor 7 could be mounted inside the transmission casing 3B.

Figure 2B shows the movement of the magnetic target 8 when different gears are selected.

Figs.3A, 3B, 6A, 63 and 60 show a follower 30 which is attached to and rotates with the selector cylinder BA, the follower BC has three detents BE, a central detent corresponding to a neutral gear position, an odd gear detent to one side of the neutral detent and an even gear detent to the other side of the neutral detent. A ball 3D is biased by a spring (indicated diagrammatically by the arrow S' on Figs. 6a, 63 and 60) for engagement with one of the detents 3E. The ball 3D is slidingly supported by the transmission casing BB either directly or via a bracket. It will be appreciated that the ball 3D could be replaced by a spring biased pin having a hemi-spherical end. The detents BE define first, second and third rotational positions corresponding to a selection position for a first row of gears, a selection position for a second row of gears and a neutral position for the transmission 3 and in particular the peaks located between the neutral detent and the in-gear detents determine whether upon releasing the gear lever 11 the transmission 3 will move into gear (pull-in) or into neutral (no pull-in) as will be described in greater detail hereinafter.

Starting with the transmission 3 it can be seen that there is a physical link to the magnetic target 8 in the form of the mechanical connection of the magnetic target 8 to the selector cylinder BA and a physical connection to the selected gear sensor 7 in the form of the mechanical -1l -connection of the selected gear sensor 7 to the transmission housing 3B.

There is a flux connection between the selected gear sensor 7 and the magnetic target 8 such that variations in flux can be sensed by the selected gear senscr 7 to provide a signal indicative cf the axial and rotational positions of the selector cylinder 3A and hence whether the transmission 3 is in an odd gear, an even gear or neutral and which one of the odd and even gears is engaged.

The selected gear sensor 7 continuously outputs signals indicative of the rotational and axial positions of the selector cylinder 3A and these are used to predict the next gear to be engaged by comparing the output signals with various check values.

For example, by carrying out test work datum or safe pull-in rotational positions of the selector cylinder 3A can be established. The even and odd gear pull-in positions are shown in Figs. 6B and 60 respectively.

In Fig.6A the selector cylinder 3A is shown in the neutral position and in Figs. 6B and 60 the selector cylinder 3P is shown in positions corresponding to an even pull-in position (EPI) and an odd pull-in position (OFI) . The even pull-in position in this case is reached when the selector cylinder 3P. is rotated Q degrees from the neutral position and the odd pull-in position is reached when the selector rotation cylinder 3A is rotated -degrees from the neutral position.

Clockwise rotation of the selector cylinder 3A is represented on Figs. 6A to 60 as a positive angle and counter clockwise rotation as a negative angle.

If the rotational position at which these pull-in positions (EPI and OFI) are reached is known and the selected gear sensor 7 is calibrated such that the transmission state -12 -module 5 is able to determine from the signals received from the selected gear sensor 7 when these calibrated rotational positions in a gear engaging direction are reached by setting calibration values corresponding to these positions, then these calibrated values can be used to predict, before a gear is actually engaged, whether the engaged gear will be an odd gear or an even gear. By combining this information with the axial position of the selector cylinder 3A determined from the axial position signal generated by the selected gear sensor 7 the transmission state module 5 is able to predict the next gear to be engaged.

It will be appreciated by those skilled in the art that the respective odd and even pull-in positions are the rotational is positions of the shift cylinder 3A where, the various forces acting will rotate the shift cylinder 3A so that the ball 3D fully engages with the respective detent 3E and the corresponding gear will be engaged. That is to say, at and beyond the pull-in position the transmission 3 will automatically be pulled into gear and before the pull-in position is reached the transmission will revert to a neutral gear position.

Referring now to Figs 7A and 73 the two inputs to the transmission state module 5 from the selected gear sensor 7 in the form of a sensed rotational position signal (Y axis) and a sensed axial displacement signal (X-axis) are shown.

In more detail, the selected gear sensor 7 outputs a PWM signal which is either in range (between 10% and 90% in this case) or out of range (>90% or < 10% in this case) Input driver software in the transmission state module 5 interprets the PWM and, if the PWI'4 is out of range (>90% or < 10%) the input driver software sets a quality signal to FAULT. It will be appreciated that the 10 to 90% range is provided by way of example and that the invention is not limited to the use of such a range.

-13 -If the PWM signal is in range (between 10% and 90%) the input driver software sets the quality signal to OK. The transmission state module 5 then compares the PWI4 signal to thresholds to determine whether neutral is or is not selected, an odd gear is or is not selected, an even gear is or is not selected the odd gear pull-in position (DPI) has been reached and the even gear pull-in position (EPI) has been reached. Furthermore, the transmission state module 5 adaptively calibrates the Y axis output from the selected gear sensor 7 during operation to provide updated values for the calibration values corresponding to the DPI' and the EPI' as discussed later with respect to Figs. BA to 9.

It can be seen on Fig.7A that the six speed transmission has is a conventional H-gate arrangement with the odd gears and reverse arranged in one row and the even gears arranged in another row and that the gears are arranged in a number of gear shift lever planes in which there are arranged reverse gear, and then in the remaining planes two forward gears namely first and second gear (1/ 2 plane), third and fourth gears (3/ 4 plane) and fifth and sixth gears (5/ 6 plane) Referring now to Fig.7B if the PWI4 signal is substantially 90% then the transmission state module 5 interprets this as an indication that one of the even gears has been selected, if the PWM signal is substantially 10% then the transmission state module 5 interprets this as an indication that one of the odd gears has been selected, if the PWI4 signal is substantially 50% then the transmission state module S interprets this as an indication that neutral has been selected.

It will be appreciated that there may in practice be tolerance bands on all of these figures and, for example, the transmission state module 5 may well operate for the rotational direction with logic tests as follows:- -14 -If 851< PWM < 901 Then engaged gear equals even; If 101< PWM < 15% Then engaged gear equals odd; If 451< PWM < 55% Then gear equals neutral.

In addition to these in-gear evaluations the transmission state module 5 also compares the rotary position signal from the selected gear sensor 7 with the two rotational calibration values for the even gear pull-in position (EPI) and for the odd gear pull-in position (OPT) which are used to predict the next gear to be engaged. Initially these calibration values are set to the datum or safe calibration values referred to above but as discussed later in accordance with this invention these calibration values are adaptively re-calibrated during use of the transmission 3.

For example, as shown on Fig.73, upon the first use of the transmission the transmission state module 5 performs for the rotational direction the following logic tests:-If PWF4< 25% Then predicted next gear equals odd; If PWF4> 75% Then predicted next gear equals even.

Where, the datum or safe pre-defined rotational calibration values EPI and OPT are 75% and 25% respectively.

These initial calibration values are very safe calibrated values where it is known that the respective pull-in positions will have been reached.

Using this logic the transmission state sensor 5 is able to predict by combining it with the axial position of the shift cylinder BA the next to be engaged gear before it is actually engaged. This information can then be sent several milliseconds earlier (20-4Oms) to other control systems requiring knowledge of gear selection such as a UMI gear indicator or the engine control unit 6 before the gear is actually engaged.

-15 -It will be appreciated that the selected gear sensor 7 could also be arranged such that when the transmission 3 is in neutral the corresponding nominal sensor signal is 50%, when the gear lever is moved forwards into one of the odd gears the sensor signal increases above 50% and when one of the even gears is selected the sensor signal decreases below 50% and so the logic tests given above would be reversed in sense e.g. for the first use of the transmission:-If 851< PWM < 90% Then engaged gear equals odd; If 101< PWM < 15% Then engaged gear equals even; If 451< PWM < 55% Then gear eguals neutral.

If PWI'4< 25% Then predicted next gear equals even; is If PWF4> 75% Then predicted next gear eguals odd.

Referring back to Fig.7A the output signal from the selected gear sensor 7 for the axial or X axis direction is shown and it can be seen that for the six speed transmission shown by

way of example:

If PWF4 = 10% Reverse gear plane is selected; it PWF4 = 40% first/ second gear plane is selected; If PWI'4 = 70% third/ fourth gear plane is selected; If PWF4 = 90% fifth/ sixth gear plane is selected; The transmission state module 5 can then combine the X and I axis outputs to predict the next gear to be engaged and also to confirm the gear actually engaged.

It will be appreciated that as referred to in respect of the rotational calibration the axial position calibration could be the opposite of that described above with 10% = sixth -16 -gear and 90% = Reverse in which case the logic tests for the plane would be different to those given above.

Although the selected gear sensor 7 has been described with respect to the use of a PWM magnetic selected sensor which uses a 2D magnet and generates PWN outputs, the invention is not limited to the use of sensors producing a PWN output it is egually applicable for use with a displacement sensor which generates variable voltage outputs instead of PWM outputs.

It will also be appreciated that the selected gear sensor 7 is not limited to the use of a single 2D magnetic sensor array 7 it may also be put into effect using a 3D sensor array and magnet arrangement or two separate sensors one for sensing rotary motion and one for sensing axial motion.

It will also be appreciated that the use of a selected gear sensor is not limited to a six forward speed transmission or to the positioning of reverse gear as shown in Fig. 7A and that a selected gear sensor could be applied to transmissions having a different number of forward speeds or a different reverse gear position with equal benefit.

Furthermore, although the selected gear sensor has been described above with respect to its use with a shift turret selector cylinder 3A that rotates when the gear lever 11 is moved forwards and backwards in gear engaging directions to select respectively odd and even gears and moves axially when the gear lever 11 is moved left and right to change the gear shift lever plane in which the gear lever moves, this need not be the case.

For example, the shift selector member could move axially when the gear lever 11 is moved forwards and backwards in gear engaging directions to select respectively odd and even gears and move rotationally when the gear lever 11 is moved -17 -left and right to change the gear shift lever plane in which the gear lever moves. With such an embodiment the oalibration values for pull-in would not correspond to rotational positions but would correspond to axial positions of the shift selector member.

It will be appreciated that the time taken for a driver to move a gear shift lever U from one gear position to another gear position is relatively short and so any additional information provided early in a gear change is potentially very useful to a system requiring knowledge of the selected gear.

For example, with a GSH system knowing early in the gear change that the gear change is an upshift allows the GSH system to begin reducing the engine speed and conversely knowing early in the gear change that the gear change is a downshift allows the GSH system to begin increasing the engine speed.

Referring now to Figs. 8A to 9 a method according to this invention for adaptively calibrating during use of the motor vehicle 1 the odd and even pull-in calibration values will be described.

Fig.9 shows the basic steps required to perform a calibration method according to the invention and Figs.8A and 8B show respectively the motion of the shift turret selector cylinder 3A in a gear engaging direction (Y axis) during a first to second gear shift and the velocity of the shift turret selector cylinder 3A during the gear shift.

Referring to Fig.9 the method starts at box 50 with a key-on event and then advances to box 60 where a gear shift is initiated by in this case the disengagement of the clutch 10 by a driver.

-18 -The method proper then commences at step 120 by the monitoring by the transmission state module 5 of the position of the shift selector member in the form of the shift turret selector cylinder 3A in a gear engaging direction (Y axis) . That is to say, the rotational position of the shift turret selector cylinder 3A is monitored. In practice the I axis motion will be continuously monitored after the key-on event has occurred and the X axis position of the shift turret selector cylinder 3A will also be continuously monitored by the transmission state module 5.

The method then advances to box 122 where it is determined whether the shift turret selector cylinder 3A is moving away from a position associated with neutral. Referring to Fig.8A it is known that neutral occurs at an output of substantially 50% therefore this first test ensures that the shift turret selector 3A is moving into a gear engaging position and not out of a gear engaging position. That is to say, with the output shown in Fig.8A, a time after the position N' If the output from the I axis sensor indicates that the shift turret selector BA is moving towards neutral, that is to say in the example shown, at a time prior to the location of position N' the method cycles back to box 120.

Conversely, if the shift turret selector 3A is moving in a gear engaging direction, that is to say in the example shown, the time is a time after the position N' the method advances to box 125 where the velocity of the shift turret selector BA in the gear engaging direction is determined.

In this case the velocity is determined by differentiator (not shown) forming part of the transmission state module 5 which differentiates the I position signal from the selected gear sensor 7. The differentiator produces a velocity output as shown in Fig.83.

-19 -The transmission state module 5 then analyses the velocity output to determine whether pre-defined characteristic velocities are present as indicated in box 130.

If these pre-defined characteristic velocities are not found the method advances to box 135 to determine whether a key-off event has occurred and if it has the method ends in box 500. If a key-off event has not ocourred then the method advances to box 140 to determine whether the clutch 10 has been engaged. If the clutch 10 has been engaged, then no re-calibration takes plaoe and the method return to a point prior to box 60 to wait for the next clutch disengagement.

That is to say, if by the end of the gear shift the characteristic velocities cannot be identified a new calibration value cannot be found and so the transmission state module 5 in this case uses an existing value for the respective pull-in position when the next gear shift occurs.

If the clutch has not been engaged in box 140 the method returns to boxes 125 and 130 to check again whether the pre-defined characteristic velocities can be found.

Referring back to box 130 if the pre-defined characteristic velocities are found to be present then a new value for the calibration value or pull-in position is generated as described below.

The predefined characteristic velocities are a period of time in which the velocity of the shift turret selector 3A remains substantially zero and a spike in velocity following the period of substantially zero velocity.

Referring to Fig.8B a period of substantially zero velocity is indicated by the arrow V and a spike following this period of substantially zero velocity is indicated by the arrow EPI' . When this combination of pre-defined -20 -characteristic velocities has been found the transmission state module 5 determines the location of the peak value of the spike and uses the location of the spike as an indicator of the position of the shift turret selector IA when the pull-in position is reached. That is to say, by knowing when the peak velocity occurs the transmission state module can convert this into an equivalent position output. For example, in the case of the first to second gear shift shown in Figs. 8A and SB, the peak occurs at 62.8 seconds and so the pull-in position will correspond to the position of the shift turret selector 3A at 62.8 seconds which in this case is 73%.

The method then advances to box 150 where the calibrated pull-in value is updated based upon the newly acguired calibration value. This may be a simple replacement of the existing value with the new value or may be based upon combining the current calibrated value with the newly acguired calibration value.

For example, in the case of the first gear change executed by the transmission when it enters service or during pre-delivery calibration such as end-of line calibration, the calibration value for second gear will be set at the safe datum value of 75%. If, as referred to above, the newly acguired calibration value is 73% then the updated calibration value could be 73% or could be based upon an eguation such as the equation:-Updated Calibration value = CP0 + [ (CPW -CP01j / N] Where: - = existing value of calibration value; = new acquired value of calibration value; and N = a number egual to or greater than 1.

Using the above values and N=l0 -21 -The updated calibration value = 75 +[(73 -75)/ic] = 74.8 The use of such a combining technique will result in the updated calibration value converging to a value of 731 but reduces the risk of system Instability or failure if an unsafe value of CP, is produced.

It will however be appreciated that other mathematical methods or techniques could be used to update the calibration value.

Once the updated calibration value which in this case is an even gear pull-in position has been determined it is stored in the transmission state module 5 and used in the next gear shift cycle as the value for the even gear pull-in position.

It will be appreciated that a similar technique is used to adaptively update the calibration value used for odd gears, namely, the odd gear pull-in position.

It will also be appreciated that instead of producing only odd and even gear calibration values, separate calibration values could be produced for each gear. This has the advantage that any slight differences in the mechanical arrangement due for example to different wear rates that result in slight variations in pull-in position for different gears in the same row will automatically be compensated for.

Referring back to Fig.9, after updating the calibration value in box 150 the method advances to box 200 where it is determined whether a key-off event has occurred and if it has the method ends at box 500 but, if it has not, the method goes back to box 60 via box 70. Note that box 70 is only present to indicate that the clutch 10 must be engaged and then subsequently disengaged at box 60 in order to restart the calibration cycle at box 120. It will be -22 -appreciated that other means could be used to initiate the calibration cycle and the invention is not limited to the use of clutch position.

Therefore, while a key-on state exists, the calibration method will continuously be repeated for every gear change so that each calibration value is adaptively updated based upon changes in the operating state of the transmission 3 and the gear shift mechanism. The use of a calibration value based upon the use of a maximum velocity enables the time at which pull-in occurs to be more accurately established compared to the use of a datum or safe calibration value and so provides a small decrease in the time reguired to provide a next to be engaged gear prediction. This is because a datum or safe calibration value has to be very conservative in order to ensure that it is safe but an adaptively obtained calibration value is able to be set where pull-in occurs in practice and this position will be reached during a gear change before the datum or safe value.

The invention therefore provides a method that can be used to initially calibrate the selected gear sensor and also can be used to adaptively calibrate the selected gear sensor during use.

It will be appreciated by those skilled in the art that although the invention has been described by way of example with reference to one or more embodiments it is not limited to the disclosed embodiments and that one or more modifications to the disclosed embodiments or alternative embodiments could be constructed without departing from the scope of the invention as set out in the appended claims.

Claims

<claim-text>-23 -Claims 1. A method for calibrating a selected gear sensor for a multi-speed manual transmission having an H-gate shift mechanism in which the selectable gears are arranged in two rows and in a plurality of parallel gear shift lever planes and the shift mechanism includes a shift selector member that is moveable by a gear shift lever in rotational and axial directions to effect engagement of the selectable gears wherein the method comprises monitoring the movement of the shift selector during a gear shift using the selected gear sensor to provide an output indicative of the motion of the shift selector member in a gear engaging direction converting the motion in the gear engaging direction into a velocity in the gear engaging direction and using pre-defined characteristic changes in velocity to produce a calibration value in the gear engaging direction.</claim-text> <claim-text>2. A method as claimed in claim 1 wherein producing a calibration value comprises locating the position where a peak velocity occurs and using the location that the peak velocity occurs as the calibration value.</claim-text> <claim-text>3. A method as claimed in claim 2 wherein producing further comprises using a period of substantially zero velocity followed by a spike in velocity to identify the position where the peak velocity occurs.</claim-text> <claim-text>4. A method as claimed in any of claims 1 to 3 wherein the method further comprises using the output from the selected gear sensor to confirm that the shift selector member is moving away from a neutral gear position and only producing a calibration value if the shift selector member is confirmed to be moving away from the neutral position.</claim-text> <claim-text>-24 - 5. A method as claimed in any of claims 1 to 4 wherein the method further comprises updating the calibration value after every gear shift.</claim-text> <claim-text>6. A method as claimed in claim 5 wherein updating comprises combining the latest calibration value with a previous calibration value to produce the updated calibration value.</claim-text> <claim-text>7. A method as claimed in any of claims 1 to 6 wherein the method further comprises producing a first calibration value for all of the gears arranged in one row of the two rows of gears and producing a second calibration value for all of the gears in the other row of the two rows of gears.</claim-text> <claim-text>8. A method as claimed in any of claims 1 to 6 wherein the method further comprises producing a separate calibration value for all of the gears.</claim-text> <claim-text>9. A method as claimed in any of claims 1 to 8 wherein the calibration value corresponds to a pull-in position.</claim-text> <claim-text>10. A method as claimed in any of claims 1 to 9 wherein the shift selector member is moved in a rotational direction to produce motion in a gear engaging direction and the calibration value corresponds to a rotational position of the shift selector member.</claim-text> <claim-text>11. A selected gear sensing system for a multi-speed manual transmission having a H-gate shift mechanism including a shift selector member that is moveable in response to movement of a gear shift lever in rotational and axial directions wherein the system comprises a first sensor to sense rotational motion of the shift selector member, a second sensor to sense axial motion of the shift selector member and an electronic processing unit to receive and process the signals from the first and second sensors, the -25 -electronic processing unit being operable to monitor the movement of the shift selector during a gear shift using the selected gear sensor to provide an output indicative of the motion of the shift selector member in a gear engaging direction, convert the motion in the gear engaging direction into a velocity in the gear engaging direction and use pre-defined characteristic changes in velocity to produce a calibration value in the gear engaging direction.</claim-text> <claim-text>12. A system as claimed in claim 11 wherein producing a calibration value comprises locating the position where a peak velocity occurs and using the location that the peak velocity occurs as the calibration value.is 13. A system as claimed in claim 12 wherein producing further comprises using a period of substantially zero velocity followed by a spike in velocity to identify the position where the peak velocity occurs.14. A system as claimed in any of claims 11 to 13 wherein the electronic processing unit is further operable to use the output from the selected gear sensor to confirm that the shift selector member is moving away from a neutral gear position and only producing a calibration value if the shift selector member is confirmed to be moving away from the neutral position.15. A system as claimed in any of claims 11 to 14 wherein the electronic processing unit is operable to update the calibration value after every gear shift.16. A motor vehicle having a predictive selected gear sensing system as claimed in any of claims 11 to 15.17. A method for calibrating a selected gear sensor substantially as described herein with reference to the accompanying drawing.-26 - 17. A selected gear sensing system for a multi-speed manual transmission substantially as described herein with reference to the accompanying drawing.18. A motor vehicle substantially as described herein with reference to the accompanying drawing.</claim-text>